Differential buffer.



F. G.\sH0RTT. DIFFERENTIAL BUFFER. APPLICATION FILED. DEO. 22, 1902.

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PATENTBD OCT. 13, 1903.

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To all whom it may concern:

EDWARD Gr. SHORTT, OF CARTHAGE,

Patented October 13, 1903.

PATENT OFFICE.

GOODWINEMERY, OF CLAYTON, NEVVYORK.y

DIFFERENTIAL BUFFER.

SPECIFICATION forming part of Letters Patent No. 741,558, dated October 13, 1903.

I Application tiled December 22, 1902. Serial No. 136,196. (No model.)

Be it known that I, EDWARD G. SHORTT, a citizen of the United States of America, and

a resident of Carthage, in the county of Jef-"i ferson and State of New York, have invented certain new and'useful Improvements in Differential Buers, of which the following is af specification.

My invention relates to certain new and useful improvementsin buffers for railwayv or tram cars or other vehicles, as well as for parts of machinery and other constructions where shocks or collisions incident to the -parts in all the figures.

more or less violent impact of the parts upon' each other during mechanical movements or F being at other times large and severe, so as to tend to seriously damage and strain the cars being coupled or the operative parts of the mechanism that are being brought'together.

The object of my invention is to provide a buing means that will accommodate itself with great elasticity to severe as well as to light blows, so that the coupling of cars, for

example, may be eifected without a violentl 3 `vehicle,vor other carriage, being offered simand rude shaking of the cars orn carriages to which couplers are attached.' I accomplish this object by providing a buffer that will aiford a yielding resistance to the shocks encountered in coupling the cars, said resistance differing in degree at dierent times'or being variable, so as to suit the needs of different cases.

The buffer consists, essentially, in a liquid or fluid containingchamber wherein is a piston and combined with the latter springs or other yielding means, the liquid being noncompressible and being displaced Yby the piston during reci'procations'of thev latter, and thus having the .volume or quantity varying at opposite ends of the piston during the movements 'of the'latt'er; and the invention also consists, essentially, in the construction, arrangement, and combination of thevarious mechanical parts and the relations that they sustain to each other in respect of operation and purpose,substantially as will be lmore fully hereinafter described and claimed.

In the drawings illustrating my invention, Figure 1 is a longitudinal section of my'improved variable buffer with the draw-head extended. Fig. 2 is a similar partial sectional view with-the draw-head retracted,

showing the position of the parts when the yielding mechanism of the buffer is compressed. Fig. 3 is a cross-section on the lines :n of Fig. l.

Like numerals of reference denote like 1 denotes the draw-head of a car-coupler, the said draw-head being of a common type, having the usual pivoted knuckle, as shown, or being constructed' in any other desired manner. Draw-head 1 is carried by the drawbar 2, and attachedto the inner end of 'drawbar 2 is a rod 8, constituting a continuation` lof the draw-bar and being preferably screw- YORK, ASSIGNOR TO CHARLES threaded to engage the inner end of said Adraw-bar, as shown in Fig. 1, the inner end 1 of said rod 3 passing through the piston 4 and ,being provided on its extreme end with a nut, jbetween which'and a shoulder on the rod 3 ,said -piston 4 is securely clamped, so that in this way the piston 4 may be firmly connected ;to the draw-rod 3.

7 indicates the general structure of a car,

ply as an outline form by way of example lonly, and this structure 7. carries the coup` ling and bung mechanism. Attached to iframe 7 in a secure and rigid manner is the ybuffer body or casing 5, having numerous inlternal cavities for the accommodation of mechanical devices and also a quantity of oil or other suitable non-freezing and non-compressible fluid or liquid, said internal cavities being communicable with each other in the .manner 'and through theports or passages Ioo is fastened to the main piston or ram 4, which reciprocates closely within a main cylindrical chamber 6. At one end of piston 4 is a spiral spring 11, tensioned between the piston and the opposite end of the cylindrical chamber 6, while at the other end of the piston 4 is another spiral spring 12, tensioned between this end of the piston 4 and the end of the cylindrical chamber 6. Obviously a pulling or pushing action on the draw-head will move the main piston 4 in one direction or the other and cause the springs to be compressed. These springs are of much greater strength and tension than is necessary to allow the car when empty to be drawn without causing compression thereof, though of course conipression will take place with a loaded car. At each end of the main pistou 4, moreover, the cylinder 6 is filled with a suitable Huid or liquid-as oil, for example.

Adjacent to the cylindrical chamber 6 the body or casing 5 is provided with a constricted longitudinal passage 8, parallel to the cylindrical chamber 6, which passage communicates with the chamber 6 through certain ports, there being a port 9 between passage 8 and that part of chamber 6 containing spring 11 and there being a port 10 between passage S and that part of chamber 6 containing spring 12. Access is had to the interior chainber of the body or casing 5 whenever required through lateral apertures closed and lled by small screw-plugs 32. A port 19 leads from passage 8 to an annular groove 17 in the packing-block 1S, which groove communicates with the working surface of the rod 3 through small orifices, as shown, the object of said groove 17 being to collect any fluid leakage that may pass out of the charnber 6 along the rod 3 during the reciprocatory movements of the latter and cause a return of this leakage to the passage 8 andthe chamber 6. Thus it will be seen that I provide a confined quantity of liquid or fluid which is displaced during the movements of the piston 4, being transferred from one end of the piston to the otherand back again as the piston moves back and forth. Passage 8 communicates with a second interior chamber 22, having the function of a spring-containing chamber and which for the sake of compactness of the construction is preferably located at right angles to the piston-chamber 6. In this chamber 22 is a spiral spring 3, engaging at one end the integral boss 24 and at the other end being received into a recess in the end of a close-fitting sliding piston 20. The end of the chamber 22 is closed by a screwplug 21, against which the piston 2O abuts when the spring 22 is in its extended position, as shown in Fig. 1. The piston 20 is It will be understood, therefore, that this spring 23 offers a resistance equal to the tension of the spring to the movement of the piston 2O and to the pressure that acts against said piston. rlhi-s piston diaphragm or abutment 2O is smaller in diameter and has a face of smaller area than is the case with the main piston or ram 4, and this difference in the size of the two pistons causes the differential action of the device. A long port or passage 13 leads through the wall of the buffer body or casing 5 from the chamber 22, containing the auxiliary piston, to the main piston-chamber 6 and enters the latter chamber at two points through ports 15 and 16, which are separated from each other for a short distance. The piston 4 is provided with a central annular port 14 of sufficient length to connect the ports 15 and 16 when the piston is in its middle position, as shown in Fig. l. Midway between the middle point of the piston-chamber and the two ends of said chamber are two lateral recesses or ports 28 and 29. The piston-port 14 when the piston shifts far enough toward the left will connect the chamber-port 29 with the outlet-port 15, and when piston 4 shifts far enough toward the right the piston-port 14 will connect the chamber-port 28 with the pressure-outlet port 16. In Fig. 2 it .will be seen that pistonport 14 is connecting the lateral port 29 with the outlet-port 15. When these two ports are thus connected, the liquid contents of the piston-chamber 6 at the left of the piston 4 will be driven out through the passage 13 to a point beneath the piston 20, which latter will slide and compress the spring 23 to a greater or less extent.

Ordinarily during the coupling of cars or the interrclative movements of mechanical parts provided with my improved bufting means the shocks or collisions Will be so slight that the piston 4 will have a range of movement slight in extent and there will be only a small amount of compression imparted. to the springs 11 and 12, for their resiliency will be competent to resist these smaller shocks; but when a movement of greater strength occurs the effect will be to compress one or the other of the springs and to force the confined body of liquid from one end of the piston-chamber to the other-that is to say, as one end of said chamber is emptied of its contents incident to the action of the piston the other end of the chamber will be correspondingly filled. The spring 23 and auxiliary piston 2O will not be called into play except during Very severe shocks. When the pulling or pushing action of the main piston 4 is so great as to force said piston past the transfer-ports 9 or 10 and also to connect port 29 with port 15 or port 28 with port 16, the springs 11 and 12 will be inadequate to resist the shock, as also will be the movement of the confined body of the liquid under the action of the piston; but the pressure in advance of the moving piston will act through the ports just IOO IIO

may be, which is in advance of the moving.

piston, will be compressed to `its extreme limit, as shown in Fig. 2, provided the shock is severe enough, and the liquid contents at this end of. the piston Will be driven out through the port 13 into the chamber 22 or a part of said contents.

Many changes in the precise construction and embodiment of the various -parts and rearrangements and readjustments may be made without varying from the invention so long as the leading features thereof are kept prominently in mind, and-I therefore reserve the liberty of making all such changes as the exigencie's of dilerent situations may require in order to fully adapt the invention for successful extensive use.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-w 1. In a buffer, the combination of a piston, its chamber, a passage leading from one side of the piston to the other, a conned'fluid or liquid in the' chamber and passage, and an auxiliary differential device communicating with and receiving vpressure at times fromv the main piston-chamber.

2. In a buer, the combination of a piston,

its chamber, Vyielding means between the piston and the ends of the chamber, a confined quantity of fluid or liquid circulating between the ends of thepiston-cha'mber, and an auxiliary device of less diameter than the main piston, acted on by pressure from the main piston-chamber in case of leXtreme shocks.

3. In a buffer, the combination of a piston and its chamber containing fluid or liquid, an auxiliary chamber, a piston therein' having ental piston acted upon by pressure from the .ber containing a differential'device acted upon by pressure from the piston-chamber in extreme cases. y

Signed lat Carthage this 24th day of Novem-` ber, l1902. EDWARD G. SHORTT.

Witnesses:

H. G. SHORTT,

W. W. SWEET. 

